log: fix typo in comment
log: fix typo in comment

R=golang-dev, dsymonds
CC=golang-dev
http://codereview.appspot.com/6195096

Committer: David Symonds <7f6bb564ed9e580d4f0aa90d53b34578e5d24cb9@golang.org>

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang